EP 1 396 670 B1 describes the increasing trend in motor vehicles to increase the power of internal combustion engines, using superchargers which make it possible to introduce compressed charge air into the combustion space of the internal combustion engine. After the compression of the charge air, this is cooled via a charge-air cooler and subsequently delivered to the combustion space. The routing of the charge air between the individual assemblies takes place via charge-air hoses which have to withstand high and pulsating pressure loads and also dynamic stresses as a result of the tie-up of the charge-air hoses to the vibrating assemblies as well as high temperatures. Furthermore, high oil resistance, good adhesion of individual plies of the charge air hoses and a long service life are required. Depending on the installation conditions and the ratings, different designs of the charge-air hoses, using various types of rubber, are adopted. Thus, for example, charge-air hoses with a fluoroelastomer inner layer, with a peroxidically cross linked silicone elastomer layer constructed on it, with a reinforcing ply having strengtheners and with a silicone elastomer outer layer are employed, the fluoroelastomer inner layer serving as a barrier layer with a low permeation rate and with high heat resistance, and based on peroxidically cross-linked fluororubber, with the result that good tie-up or adhesion to the overlying silicone elastomer intermediate layer and consequently high durability can be ensured. What is described, furthermore, is the use of knits made from textile yarns, such as, for example, from meta- or para-aramids, or other yarns which have sufficiently high strength and temperature resistance, for the reinforcing ply composed of strengtheners. The publication proposes to use, for a charge-air hose, a fluoroelastomer inner layer which is cross-linked both bisphenolically and peroxidically, whereby an improved bond between the fluoroelastomer inner layer and the silicone elastomer intermediate layer can be achieved. The fluoroelastomers are cross-linked fluororubbers (FKM), and fluororubbers can be obtained by the copolymerization or terpolymerization of the following monomers: vinylidene fluoride (VF2), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), 1-hydropentafluoropropylene (HFPE), perfluoro(methylvinylether) (FMVE). In addition, monomers with reactive groups can be incorporated into the polymer chain in order to facilitate cross-linking. All organic peroxides known to a person skilled in the art of fluororubber cross-linking, for example 2,5-dimethyl, 2,5-di-(tert-butylperoxy)hexane or dicumyl peroxide, which are usually employed with suitable coactivators, for example triallylisocyanurate, should be used as peroxidic cross-linking chemicals. All systems known for the cross-linking of fluororubbers, for example with bisphenol A or AF, may likewise be used as bisphenolic cross-linking systems, the systems usually being composed of the cross-linking agent (bisphenol), of an accelerator (for example, phosphonium salt) and of a base (for example, a combination of calcium hydroxide and magnesium oxide). Fluororubbers are also obtainable in which the bisphenolic cross-linking system is cointegrated into the rubber. The publication proposes, furthermore, to use as the elastomer outer layer a peroxidically cross-linked silicone elastomer outer layer which, during vulcanization, makes it possible to have an optimal bond with the silicone elastomer intermediate layer which partially penetrates through the reinforcing ply. It is also proposed to use in the charge-air hose a winding process for forming the reinforcing ply. A tie-up of the charge-air hoses to the assigned assemblies of the motor vehicle is to take place by means of what are known as Henn couplings.
DE 10 2004 051 073 A1 builds on the assumption that, for charge-air hoses subjected to high dynamic load, manufacture must take place from yarns with endless filaments, whereas only hoses not loaded dynamically are reinforced with strengtheners in the form of fabric ribbons made from short fiber stable yarns with a filament length of 10 to 60 mm, which will not be suitable for the dynamically highly loaded charge-air hoses which may possess complicated geometry, since sufficient strength will not be generated thereby. The publication proposes to form the textile strengtheners with a meta-aramid yarn or twist of the “stretch broken” type composed of filaments with a length of 200 to 1400 mm, the fineness of the yarns or twists being 1000 to 10 000 dtex, preferably 3000 to 8000 dtex. Yarns or twines of the “stretch broken” type are yarns or twines which are spun from a large number of individual filaments and are then fixed and subsequently drawn apart. The filaments consequently tear in an undefined way and project partially out of the yarn or twine. Meta-aramid yarns of the “stretch broken” type possess high strength and temperature resistance and also a modulus of elasticity which is lower in the stretch range by up to approximately 8%, at a temperature of 200° C., than in the case of meta-aramid yarns composed of endless filaments. In the working range of elastomeric products, the modulus of elasticity of embedded elastomer and that of embedded yarn are approximately equal. Thus, there is a reduction in the cutting of the strengthener into the elastomer during use, which ultimately should lead to an increase in the service life of the products. It is mentioned that at least one reinforcing ply present between elastomer plies and composed of the textile strengtheners in the form of “stretch broken” yarns may be present in a charge-air hose. The reinforcing ply may be in the form of a knit. The elastomer plies of the charge-air hose may be based on hydrated nitrile rubber, silicone rubber, fluororubber or acrylate fluororubber. In addition to the knit ply and the embedded elastomer plies, the charge-air hose can also have further plies and layers, such as, for example, further inner and outer layers or plies composed of different polymeric materials. The charge-air hose is produced by means of conventional processes, for example by the strengthener ply being applied by means of suitable processes to an extruded rubber mix inner layer and subsequently the rubber mix outer layer being applied thereto at the extrusion process. The hose is then vulcanized by means of conventional processes.
DE 34 45 282 A1 relates to a rectilinear line pipe for underground placement by means of concrete forms, and for one embodiment two non-coaxial pipes oriented parallel to one another are foamed around in the line pipe and are protected externally by an outer pipe. Both the inner pipes and the outer pipe are produced from plastic with reinforcement composed of fiber knit. Production is carried out by applying individual plies to an inliner which is provided as a semifinished product and which constitutes a core pipe. The line pipe serves for heat-insulated transport of gaseous and liquid media, during which leak tightness is of primary importance in addition to heat insulation, but there is no thermal or dynamic stress upon the line pipe.
GB 1,146,872 also relates to a hose, to be precise a straight hose for hydraulic applications with essentially static pressures up to 17.5 bar. Manufacture is by extrusion on a mandrel. The hose possesses an inside diameter of 6.3 mm, while the outside diameter amounts to 14.7 mm. What is used as a reinforcing ply is a braiding composed of monofilaments sheathed individually with a thermoplastic material, rubber or PVC by extrusion and composed of nylon, rayon, polyethylene terephthalate or polypropylene, the braiding produced then being glued together by “baking” the sheathing.
U.S. Pat. No. 6,807,988 also relates to a non-generic straight hose for the conveyance of fluids under pressure, which is manufactured on a core pipe and is reinforced thermoplastically. The hose is used for mobile and industrial hydraulic applications with pressures up to 82.7 MPa. The core pipe may be of multilayer form with an inner layer or lining having high chemical resistance to prevent swelling, crazing, stress cracking and corrosion, and with resistance to attacks by weakly acidic or alkaline solutions, phosphate ester solutions and alcohols and also organic solvents, hydrocarbons or inorganic solvents. Two to eight or more reinforcing layers are arranged over the core pipe in the pipe walls and may in each case be braided, knitted or packaged in the conventional way. Exemplary embodiments with spiral helical windings having oppositely oriented spiral turns are illustrated. The yarn is wound helically under tension in one direction, that is to say either round to the left or round to the right, while the next immediately following layer is wound in the opposite direction. A variation in the twist of the winding is also proposed, whereby a fatigue strength under bending and a pressure resistance of the hose and also the costs are to be optimized. To reduce the axial stretch for high-pressure applications, the angle of the spiral winding must be optimized in an angular range of 40° to 65° with an optimum at 54.7°, with the result that a “neutral pitch angle” is to be formed. The individual turns lie directly one on the other. An adhesion promoter is employed between individual layers.
United States patent application publication 2006/0223399 A1 discloses a hose which is manufactured on a mandrel and which is obviously intended for hydraulic applications. A single fiber is either braided or spiral wound here onto an extruded non-vulcanized pipe in order to form a fiber reinforced ply. After an intermediate layer has been applied to this reinforcing ply, a further fiber is wound spirally and is pressed into the circumferential surface of the intermediate layer.
U.S. Pat. No. 5,077,018 discloses a hose in which a fiber provided with a dip coating is employed. The hose is manufactured on a mandrel which stipulates a rectilinear longitudinal axis and a constant cross section of the final product. An exemplary embodiment with two reinforcing plies composed of braided fibers is illustrated.